You can associate supported file formats with 5Dfly. When you open a file from Windows Explorer that is associated with Fly Free Photo Editing & Viewer, 5DFly opens and displays the file in the Viewer.
To associate a file with Fly Free Photo Editing & Viewer:
Click Menu (the first button in toolbar), and select Options -> File Associations.
Do each of the following:
select the check boxes next to the image file formats that you want to associate with Fly Free.